1. Field of the Invention
The invention relates to a method of transferring a colored decoration to an article using a liquid on which the colored decoration floats and into which the article is immersed in order to transfer the colored decoration to the article.
2. Description of the Related Art
U.S. Pat. No. 4,010,057, corresponding to German Patent No. DE-A-25 34 640, describes a method and apparatus for applying a decoration to an article using hydrostatic pressure. This patent is hereby incorporated by reference. However, this patent neither teaches nor suggests the use of transferring the decoration from one support to another prior to transferring the decoration to an article.
U.S. Pat. No. 4,348,246 describes a transfer printing technique in which the film with the decoration to be transferred is not placed upon a layer of water but instead is placed upon a layer of granules of such fine grains that the decoration and the supporting granules conform to the curved surface of the article, thereby enhancing the contact of the decoration against the article.
U.S. Pat. No. 4,388,866 describes a transfer printing technique in which the film with the decoration to be transferred is placed upon a deformable layer of pins which can be adapted to the shape of the article, thereby enhancing the contact of the decoration against the article.
U.S. Pat. No. 4,436,571 describes a transfer printing technique in which the article to receive a decoration is immersed in a specific way into a flowing liquid with the decoration floating thereupon. The article is presented to the decoration in a continuous movement in the general direction of the liquid flow along a downward path oblique to the surface of the liquid and then along an upward path oblique to the surface of the liquid to provide contact between the decoration and the article.
U.S. Pat. No. 4,229,239 describes another transfer printing technique in which the decoration is prepared before the transfer by a solvent in order that it detaches itself more easily from the supporting film.
U.S. Pat. No. 4,407,881, corresponding to DE-A-32 19 992, describes a transfer printing technique in which the decoration is supported on a layer of a special film made of a hydrophilic, deformable layer which can swell by absorption of water, and a further layer which is placed over the hydrophilic layer and is varyingly permeable to water so that the hydrophilic layer expands to a greater or lesser extent.
U.S. Pat. No. 4,231,829 describes another transfer printing technique in which boric acid or a salt thereof is added to a PVA film supporting the decoration on the liquid or to the water on which the decoration floats in order to promote the transfer process.
U.S. Pat. No. 4,269,650 also describes a transfer printing technique utilizing the addition of a solvent in order to make the detachment of the decoration from the supporting film easier.
European Patent Application No. EP 0 573 676 A1 describes the use of a support having a release characteristic for applying colored decoration to a substrate. In this prior art document, the colored decoration is first applied to a support having a release characteristic. A coating material is then applied over the colored decoration which has been applied to the support. The coating material is subsequently subjected to partial cross linking, and then, under pressure and/or elevated temperature, the partially cross linked coating material together with the colored decoration is transferred from the support to the substrate which is ultimately to be decorated. This transfer takes place in such a way that the coating material lies on the substrate under the colored decoration. Finally, further cross linking of the coating material takes place on the substrate.
In transfer printing the colored decoration (also called the printing pattern) is on a film, which supports the decoration. The colored decoration and film are floated on a water surface where they are extended (stretched) and/or condensed (compressed). For this extending or condensing of the floating decoration and film, the prior art discloses air blowers which are arranged over the decoration and film to extend and/or to condense the decoration with the film by means of an air flow, i.e., to expand it in certain directions, depending on the shape of the article to be printed, and, if appropriate, to compress it in other directions.
The use of a liquid filled tank to support a decoration for applications to an article is also known and is considered to be prior art.
U.S. patent application Ser. No. 08/946,802 filed Oct. 8, 1997 now U.S. Pat. No. 6,001,206 issued Dec. 14, 1999, entitled "Method and Apparatus for Applying a Decoration to an Article"; U.S. Pat. No. 5,908,525 issued Jun. 1, 1999 and entitled "Method and Apparatus for Applying a Decoration to an Article" and U.S. Pat. No. 5,916,400 issued Jun. 29, 1999 and entitled "Method and Apparatus for Manipulating an Article for Applying a Decoration Thereon" are hereby incorporated by reference.
Typically in transfer printing a decoration from a support film wherein the article is pressed against the decoration and support film as they float upon a liquid surface, a water-soluble support film such as polyvinyl alcohol (PVA) is used.
The PVA film is relatively expensive and is largely lost in the course of the transfer printing process. In the prior art, moreover, relatively thick PVA films are required in order to accomplish the dual task of permitting the printed application of the colored decoration to be of good quality and providing the decoration with the required stability. Furthermore, the PVA films are hygroscopic and absorb water. A thinner PVA film would absorb less water and have less influence on the overall characteristics of the PVA film/decoration combination.
The object of the invention is to improve the process of transferring a colored decoration to an article by using relatively thin film to support the colored decoration on the liquid surface. The thinner support film dissolves more rapidly in the liquid. Also storage of the components used in the method is simplified.